Storage Of Allografts Research Articles

Cold Storage of Human Femoral Arteries for Twelve Months: Impact on Mechanical Properties

This biomechanical pre-clinical study aimed to assess the consequences on mechanical properties of long term cold storage (+2/+8 °C) of arterial allografts. Femoropopliteal arterial segments were collected from multiorgan donors and stored at +2/+8 °C for 12 months in saline solution with added antibiotics. Mechanical characterisation was carried out using two different tests, with the aim of defining the physiological modulus and the maximum stress and strain borne by the sample before rupture. These characterisations were carried out after 0, 6, and 12 months of storage for each sample (T0, T6, and T12, respectively). For comparison, the same tests were performed on cryopreserved popliteal femoral segments after thawing. Twelve refrigerated allografts (RAs), each divided into three segments, and 10 cryopreserved allografts (CAs) were characterised. The median (interquartile range [IQR]) Young's modulus was not statistically significantly different between the storage times for cold stored allografts: RAT0, 164 (150, 188) kPa; RAT6, 178 (141, 185) kPa; RAT12, 177 (149, 185) kPa. The median (IQR) Young's modulus of the CA group (153 [141, 185] kPa) showed no significant differences from the RA groups, irrespective of storage time. Furthermore, median (IQR) maximum stress and strain values were not significantly different between the different groups: for maximum stress: RAT0, 1.58 (1.08, 2.09) MPa; RAT6, 1.74 (1.55, 2.36) MPa; RAT12, 2.25 (1.87, 2.53) MPa; CA, 2.25 (1.77, 2.61) MPa; and for maximum strain: RAT0, 64% (50, 90); RAT6, 79% (63, 84); RAT12, 72% (65, 86); CA, 67% (50, 95). Cold storage for up to 12 months appears to have no impact on the mechanical characteristics of human arterial allografts. Therefore, this preservation method, which would greatly simplify routine care, seems feasible. Other indicators are being studied to verify the safety of this preservation process before considering its use in vivo.

24 Hours Ex-vivo Hypothermic Acellular Perfusion of Porcine Forelimb: A 7-day Follow-up Study.

One of the limiting factors for vascularized composite allograft (VCA) storage is the short viable ischemic time (4-6 hours). Hypothermic machine perfusion (MP) enables near-physiological preservation, avoiding the deleterious effects of hypoxia and static cooling. This study aims to compare muscle injury after 24-hour acellular perfusion with static cold storage (SCS) in a porcine limb replantation model, examining outcomes for up to 7 days after reperfusion. Sixteen procured porcine forelimbs were perfused hypothermic for 24 hours with Histidine-Tryptophan-Ketoglutarate (HTK, n=8) or preserved on ice for 4 hours (SCS, n=8) before orthotopic replantation. Muscle injury was assessed using biochemical markers and muscle biopsies were analyzed using the Histologic Injury Severity Score (HISS). During preservation, limb weight decreased by 2% in the SCS group and increased by 44% in the perfusion group (p<0.001). Twelve limbs (HTK, n=6; SCS, n=6) survived for 7 days. Three days after replantation, increased creatinine kinase levels were observed in the perfusion group (33781 mmol/liter versus 2163 mmol/liter; p<0.001). Mean endpoint HISS was 3.8 (SD 0.7) in the perfusion group and 1.8 (SD 0.7) in the SCS group (p=0.008), mostly due to increased edema (p=0.004). 24 hours of hypothermic MP and 4 hours of SCS of VCA demonstrated both minimal degenerated muscle tissue seven days after replantation.

Intraoperative Anesthetic Strategies to Mitigate Early Allograft Dysfunction After Orthotopic Liver Transplantation: A Narrative Review.

Orthotopic liver transplantation (OLT) is the most effective treatment for patients with end-stage liver disease (ESLD). Hepatic insufficiency within a week of OLT, termed early allograft dysfunction (EAD), occurs in 20% to 25% of deceased donor OLT recipients and is associated with morbidity and mortality. Primary nonfunction (PNF), the most severe form of EAD, leads to death or retransplantation within 7 days. The etiology of EAD is multifactorial, including donor, recipient, and surgery-related factors, and largely driven by ischemia-reperfusion injury (IRI). IRI is an immunologic phenomenon characterized by dysregulation of cellular oxygen homeostasis and innate immune defenses in the allograft after temporary cessation (ischemia) and later restoration (reperfusion) of oxygen-rich blood flow. The rising global demand for OLT may lead to the use of marginal allografts, which are more susceptible to IRI, and thus lead to an increased incidence of EAD. It is thus imperative the anesthesiologist is knowledgeable about EAD, namely its pathophysiology and intraoperative strategies to mitigate its impact. Intraoperative strategies can be classified by 3 phases, specifically donor allograft procurement, storage, and recipient reperfusion. During procurement, the anesthesiologist can use pharmacologic preconditioning with volatile anesthetics, consider preharvest hyperoxemia, and attenuate the use of norepinephrine as able. The anesthesiologist can advocate for normothermic regional perfusion (NRP) and machine perfusion during allograft storage at their institution. During recipient reperfusion, the anesthesiologist can optimize oxygen exposure, consider adjunct anesthetics with antioxidant-like properties, and administer supplemental magnesium. Unfortunately, there is either mixed, little, or no data to support the routine use of many free radical scavengers. Given the sparse, limited, or at times conflicting evidence supporting some of these strategies, there are ample opportunities for more research to find intraoperative anesthetic strategies to mitigate the impact of EAD and improve postoperative outcomes in OLT recipients.

Osteochondral Allograft Transplantation in the Knee

Osteochondral injuries of the knee can be a frequent source of debilitating pain and dysfunction. Significant chondral (>1.5-2 cm2) lesions of the femoral condyles can be especially difficult to manage with nonsurgical measures. Fresh osteochondral allograft (OCA) transplantation has been shown to be a reliable surgical procedure to manage a wide array of high-grade focal chondral lesions, with or without subchondral bone involvement. OCA transplantation affords the transfer of a size-matched allograft of mature hyaline cartilage with its associated subchondral bony scaffold. Indications include primary or secondary management of large, high-grade chondral or osteochondral defects secondary to trauma, developmental malformation, osteonecrosis, or other focal degenerative disease. Contraindications include end-stage osteoarthritis, uncorrected malalignment, ligament or meniscus deficiency, and inflammatory joint disease. Improvements in surgical technique, allograft storage, and tissue availability have created more reproducible clinical results and increased chondrocyte viability. Long-term (>10 year) graft survival rates have been shown to be between 70% and 91%, and the procedure has been shown to be cost-effective based on cost per quality-adjusted life year. Finally, OCA transplantation has been shown to provide excellent return to play rate for athletes with medium-to-large cartilage lesions. OCA transplantation is therefore an important option in the treatment algorithm of articular cartilage injuries.

Characteristics and Clinical Outcomes After Osteochondral Allograft Transplantation for Treating Articular Cartilage Defects: Systematic Review and Single-Arm Meta-analysis of Studies From 2001 to 2020.

Osteochondral allograft transplantation (OCA) treats symptomatic focal cartilage defects with satisfactory clinical results. To comprehensively analyze the characteristics and clinical outcomes of OCA for treating articular cartilage defects. Systematic review; Level of evidence, 4. We searched Embase, PubMed, Cochrane Database, and Web of Science for studies published between January 1, 2001, and December 31, 2020, on OCA for treating articular cartilage defects. Publication information, patient data, osteochondral allograft storage details, and clinical outcomes were extracted to conduct a comprehensive summative analysis. In total, 105 studies involving 5952 patients were included. The annual reported number of patients treated with OCA increased from 69 in 2001 to 1065 in 2020, peaking at 1504 cases in 2018. Most studies (90.1%) were performed in the United States. The mean age at surgery was 34.2 years, and 60.8% of patients were male and had a mean body mass index of 26.7 kg/m2. The mean lesion area was 5.05 cm2, the mean follow-up duration was 54.39 months, the mean graft size was 6.85 cm2, and the number of grafts per patient was 54.7. The failure rate after OCA was 18.8%, and 83.1% of patients reported satisfactory results. Allograft survival rates at 2, 5, 10, 15, 20, and 25 years were 94%, 87.9%, 80%, 73%, 55%, and 59.4%, respectively. OCA was mainly performed on the knee (88.9%). The most common diagnosis in the knee was osteochondritis dissecans (37.9%), and the most common defect location was the medial femoral condyle (52%). The most common concomitant procedures were high tibial osteotomy (28.4%) and meniscal allograft transplantation (24.7%). After OCA failure, 54.7% of patients underwent revision with primary total knee arthroplasty. The annual reported number of patients who underwent OCA showed a significant upward trend, especially from 2016 to 2020. Patients receiving OCA were predominantly young male adults with a high body mass index. OCA was more established for knee cartilage than an injury at other sites, and its best indication was osteochondritis dissecans. This analysis demonstrated satisfactory long-term postoperative outcomes.

Skin Bank Establishment in Treatment of Severe Burn Injuries: Overview and Experience with Skin Allografts at the Vienna Burn Center.

Depending on their extent, burn injuries require different treatment strategies. In cases of severe large-area trauma, the availability of vital skin for autografting is limited. Donor skin allografts are a well-established but rarely standardized option for temporary wound coverage. Ten patients were eligible for inclusion in this retrospective study. Overall, 202 donor skin grafts obtained from the in-house skin bank were applied in the Department of Plastic and Reconstructive and Aesthetic Surgery, Medical University of Vienna. Between 2017 and 2022, we analysed the results in patient treatment, the selection of skin donors, tissue procurement, tissue processing and storage of allografts, as well as the condition and morphology of the allografts before application. The average Abbreviated Burn Severity Index (ABSI) was 8.5 (range, 5-12), and the mean affected total body surface area (TBSA) was 46.1% (range, 20-80%). In total, allograft application was performed 14 times. In two cases, a total of eight allografts were removed due to local infection, accounting for 3.96% of skin grafts. Six patients survived the acute phase of treatment. Scanning electron microscope images and histology showed no signs of scaffold decomposition and intact tissue layers of the allografts. The skin banking program and the application of skin allografts at the Vienna Burn Center can be considered successful. In severe burn injuries, skin allografts provide time by serving as sufficient wound coverage after early necrosectomy. Having an in-house skin banking program at a dedicated burn centre is particularly advantageous since issues of availability and distribution can be minimized. Skin allografts provide a reliable treatment option in patients with extensive burn injuries.

Secondary Cold Ischemia After Normothermic Machine Perfusion: A Drawback to Centralized Organ Perfusion Centers?

Secondary Cold Ischemia After Normothermic Machine Perfusion: A Drawback to Centralized Organ Perfusion Centers?

Ex-vivo lung perfusion therapies: do they add value to organ donation?

Significant limitations in organ availability and postoperative graft dysfunction plague lung transplantation and there is continual need for innovation. Ex-vivo lung perfusion (EVLP) has emerged over the last decade as an alternative and/or complementary allograft storage and assessment tool, however logistical hurdles have limited its widespread dissemination. As such, the overall current and potential value of EVLP on modern-day lung transplantation should be considered as innovation moves forward. Since inception, EVLP has made important safety strides in conclusively showing noninferiority to cold storage in several trials. Recent advances have highlighted potential mechanisms by which EVLP in its current form may reduce the pathogenic origins of primary graft dysfunction. Exciting work on organ reconditioning with EVLP via reduction in intermediaries of acute inflammation and oxidative stress have been performed in animal models. In addition, cross-circulation during EVLP has emerged as a method to achieve more prolonged ex situ storage. The impending translation of these to clinical use will markedly improve the overall value of EVLP. This review will highlight the current status of EVLP as it pertains to overall value in lung transplantation, focusing on historical and recent preclinical work and how innovation therein will improve lung transplantation as a field.

Comparing the Paragonix LUNGguard Donor Lung Preservation System to Traditional Ice Storage

Purpose For decades, static cold storage (SCS) has been the standard for preserving donor lungs for transplant (LTx). However, questions and concerns have been raised regarding organ temperature on ice. A new preservation system (Paragonix LUNGguard; LG) was developed to maintain consistent temperatures between 4-8°C. Here, we compare short-term outcomes of recipients using LG for human LTx at a single, high-volume center to a matched SCS control group. Methods Perioperative outcomes for patients who received lungs stored via LG at our institution were collected and matched 1:2 to a contemporary cohort of patients who received lungs stored with SCS. Patients were matched based on age at LTx, lung allocation score, disease group, ischemic time, previous LTx, and pre-operative ECMO. Descriptive statistics compared perioperative outcomes between LG and SCS groups. Results 18 LG and 36 matched SCS recipients were included. Age (LG vs SCS: 61.5 vs 62.0 years, p = 0.65), lung allocation score (41.9 vs 43.6, p = 0.73), and proportion of restrictive lung disease (14, 77.8% vs 28, 77.8%, p = 1.00) were similar for recipients between cohorts. Donor age (32.0 vs 34.0 years, p = 0.67), PaO2/FiO2 ratio (423 vs 475, p = 0.24), and proportion of donation after circulatory death (3, 16.7% vs 7, 19.4%, p = 1.00) were also similar between cohorts. Median ischemic time did not differ significantly between cohorts (394 vs 395 minutes, p = 0.84). With the LG device, the median of the average allograft storage temperatures was 4.7°C (range: -0.4 - 6.1°C). During the index transplant hospitalization, LG and SCS recipients had similar rates of acute rejection (3, 16.7% vs 1, 2.8%, p = 0.10). Rates of any grade 3 primary graft dysfunction (PGD3) within 72 hours post-transplant (7, 38.9% vs 14, 38.9%, p = 1.00), PGD3 at 48 or 72 hours (3, 16.7% vs 7, 19.4%, p = 1.00), postoperative ECMO (4, 22.2% vs 6, 16.7%, p = 0.72), hospital length of stay (30.0 vs 29.0 days, p = 0.81), and 90-day mortality (1, 2.8% vs 1, 5.6%, p = 1.00) were similar between cohorts. Conclusion Compared to traditional cold storage, the LG storage system appears to be an effective alternative for lung preservation, with similar short-term perioperative outcomes after LTx. For decades, static cold storage (SCS) has been the standard for preserving donor lungs for transplant (LTx). However, questions and concerns have been raised regarding organ temperature on ice. A new preservation system (Paragonix LUNGguard; LG) was developed to maintain consistent temperatures between 4-8°C. Here, we compare short-term outcomes of recipients using LG for human LTx at a single, high-volume center to a matched SCS control group. Perioperative outcomes for patients who received lungs stored via LG at our institution were collected and matched 1:2 to a contemporary cohort of patients who received lungs stored with SCS. Patients were matched based on age at LTx, lung allocation score, disease group, ischemic time, previous LTx, and pre-operative ECMO. Descriptive statistics compared perioperative outcomes between LG and SCS groups. 18 LG and 36 matched SCS recipients were included. Age (LG vs SCS: 61.5 vs 62.0 years, p = 0.65), lung allocation score (41.9 vs 43.6, p = 0.73), and proportion of restrictive lung disease (14, 77.8% vs 28, 77.8%, p = 1.00) were similar for recipients between cohorts. Donor age (32.0 vs 34.0 years, p = 0.67), PaO2/FiO2 ratio (423 vs 475, p = 0.24), and proportion of donation after circulatory death (3, 16.7% vs 7, 19.4%, p = 1.00) were also similar between cohorts. Median ischemic time did not differ significantly between cohorts (394 vs 395 minutes, p = 0.84). With the LG device, the median of the average allograft storage temperatures was 4.7°C (range: -0.4 - 6.1°C). During the index transplant hospitalization, LG and SCS recipients had similar rates of acute rejection (3, 16.7% vs 1, 2.8%, p = 0.10). Rates of any grade 3 primary graft dysfunction (PGD3) within 72 hours post-transplant (7, 38.9% vs 14, 38.9%, p = 1.00), PGD3 at 48 or 72 hours (3, 16.7% vs 7, 19.4%, p = 1.00), postoperative ECMO (4, 22.2% vs 6, 16.7%, p = 0.72), hospital length of stay (30.0 vs 29.0 days, p = 0.81), and 90-day mortality (1, 2.8% vs 1, 5.6%, p = 1.00) were similar between cohorts. Compared to traditional cold storage, the LG storage system appears to be an effective alternative for lung preservation, with similar short-term perioperative outcomes after LTx.

Ten-year experience with cryopreserved vascular allografts in the Croatian Cardiovascular Tissue Bank.

The Croatian Cardiovascular Tissue Bank (CTB) was established in June 2011. Activities managed by CTB are processing of heart valves and blood vessels, as well as quality control, storage, medical release and distribution of allografts. The aim of this report is to present CTB's vascular tissue activities and retrospectively evaluate the outcomes of their use in the University Hospital Centre Zagreb. Between June 2011 and July 2021, 90 vascular allografts (VAs) from 55 donors after brain death were referred to CTB. Only 54% of VAs met the tissue quality requirements while 46% of tissues were discarded. The most frequent reasons for discard were unacceptable morphology and initial microbiological contamination. Altogether 42 VAs were released for transplantation and 37 of them were used in 27 surgical procedures. The most common indication for surgery was prosthetic graft or stent infection. According to the anatomic position of vascular reconstruction, patients were divided in the aortic and peripheral reconstruction group. A total of 23 patients were treated. In the aortic reconstruction group 58% of patients did not experience any graft-related complications. In the group of patients who underwent peripheral reconstruction significant incidence of reinfection was observed highlighting it as a major graft-related complication. Despite the small patient groups and limited duration of follow-up, presented clinical outcomes provide valuable information on the efficacy of vascular allografts. Additional clinical results collected on a larger patient groups and comparison to other reconstructive treatment options are necessary.

Osteochondral allograft transplantation in the knee, after prolonged fresh storage at 37 °C. Determination of viability of human cartilage allografts, indications, technique, and evidence. Follow up 10 years

BackgroundOsteochondral allografts (OA) kept fresh for a long time, are presented as a viable option for the treatment of large chondral and osteochondral lesions. GoalsChondrocyte viability decreases substantially when allografts are stored for more than 15 days. The objective of this work is to validate the viability and clinical and functional results of OA transplantation stored at 37 °C in a cell culture medium, applied in cartilage defects of the knee, defining the means and limits of allograft storage, among 15 and 28 days after extraction. Patients and MethodThis study presents the results of 20 consecutive patients, operated between 2003 and 2019, who underwent a fresh-preserved osteochondral allograft, implanted on cartilage defects of the femoral condyle and patella. The minimum follow-up time was 10 years and the maximum 17. The mean age of the patients was 29 (14−44).The clinical control data were collected using IKDC, International Knee Documentation Committee (knee-specific), KOOS, Knee injury and Osteoarthritis Outcome Score protocols. Likewise, the degree of satisfaction was evaluated. Cartilage control was performed using the International Cartilage Repair Society Score (ICRS) and the Oswestry Arthroscopy Score (OAS). Radiological evaluations were performed using MRI and helical CT. ResultsStatistically significant improvements, P < .0001, were observed for the (IKDC) (30–65); the 5 components of the KOOS protocol, (pain, 66–85); Specific symptoms, (72–82); Activities of daily living, 74–91; Sports and recreational function, from 37 to 70, related to the knee, Quality of life, (25–60). Regarding the degree of satisfaction, 89% answered being satisfied or very satisfied.The ICRS and OAS results, all patients went from grade IV to grade I, except for one who is currently in IV.The incorporation of the graft in the recipient area occurred at three months, verified by helical CT and MRI. ConclusionOsteochondral allograft transplants stored fresh at 37 °C are established as a long-term solution for the treatment of localized osteochondral defects in the knee.

Trasplante osteocondral de rodilla, mediante aloinjertos, conservados en fresco a 37 °C. Determinación de la viabilidad del cartílago humano, indicaciones, técnica y evidencia. Seguimiento mínimo, 10 años

Los aloinjertos osteocondrales (AOC) conservados en fresco de forma prolongada en el tiempo, se presentan como una opción viable para el tratamiento de grandes lesiones condrales y osteocondrales. La viabilidad de los condrocitos disminuye sustancialmente cuando los aloinjertos son almacenados durante más de 15 días. El objetivo de este trabajo es validar la viabilidad y los resultados clínicos y funcionales del trasplante de AOC almacenados a 37 °C en un medio de cultivo celular, aplicado en defectos de cartílagos de la rodilla, definiendo los medios y límites del almacenamiento de los aloinjertos entre 15 y 28 días después de la extracción. Este estudio presenta el resultado de 20 pacientes consecutivos, operados entre los años 2003 y 2019, a quienes se les practicó un aloinjerto osteocondral conservado en fresco, implantado sobre defectos de cartílago del cóndilo femoral y rótula. El tiempo de seguimiento mínimo fue de 10 años y máximo de 17. La edad media de los pacientes era de 29 (14-44) años. Los datos de control clínico fueron recogidos usando los protocolos International Knee Documentation Committee (IKDC) (específico de rodilla), Knee injury and Osteoarthritis Outcome Score (KOOS). Asimismo, se evaluó el grado de satisfacción. El control del cartílago se realizó mediante International Cartilage Repair Society Score (ICRS) y Oswestry Arthroscopy Score (OAS). Las evaluaciones radiológicas se realizaron mediante RMN y TAC helicoidal. Se observaron mejoras estadísticamente significativas, p < 0,0001 para el IKDC: 30-65; los 5 componentes del protocolo KOOS: dolor: 66-85; síntomas específicos: 72-82; actividades de la vida diaria: 74-91; función deportiva y recreativa: 37-70; relacionado con la rodilla, la calidad de vida: 25-60. En lo que respecta al grado de satisfacción el 89% respondía estar satisfecho o muy satisfecho. Los resultados ICRS y OAS, todos los pacientes pasaron del grado IV al grado I, menos uno que en la actualidad está en el grado IV. La incorporación del injerto en la zona receptora ocurrió a los 3 meses, comprobado mediante TAC helicoidal y RMN. Los trasplantes de aloinjerto osteocondral conservados en fresco a 37 °C se establecen como una solución a largo plazo para el tratamiento de defectos osteocondrales localizados en la rodilla. Osteochondral allografts (OA) kept fresh for a long time, are presented as a viable option for the treatment of large chondral and osteochondral lesions. Chondrocyte viability decreases substantially when allografts are stored for more than 15 days. The objective of this work is to validate the viability and clinical and functional results of OA transplantation stored at 37 °C in a cell culture medium, applied in cartilage defects of the knee, defining the means and limits of allograft storage, among 15 and 28 days after extraction. This study presents the results of 20 consecutive patients, operated between 2003 and 2019, who underwent a fresh-preserved osteochondral allograft, implanted on cartilage defects of the femoral condyle and patella. The minimum follow-up time was 10 years and the maximum 17. The mean age of the patients was 29 (14-44). The clinical control data were collected using International Knee Documentation Committee (IKDC) (knee-specific), Knee injury and Osteoarthritis Outcome Score (KOOS) protocols. Likewise, the degree of satisfaction was evaluated. Cartilage control was performed using the International Cartilage Repair Society Score (ICRS) and the Oswestry Arthroscopy Score (OAS). Radiological evaluations were performed using MRI and helical CT. Statistically significant improvements, P <.0001, were observed for the IKDC: 30-65; the 5 components of the KOOS protocol, pain; 66-85; specific symptoms: 72-82; activities of daily living: 74-91; sports and recreational function: 37-70; related to the knee, quality of life: 25-60. Regarding the degree of satisfaction, 89% answered being satisfied or very satisfied. The ICRS and OAS results, all patients went from grade IV to grade I, except for one who is currently in IV. The incorporation of the graft in the recipient area occurred at three months, verified by helical CT and MRI. Osteochondral allograft transplants stored fresh at 37 °C are established as a long-term solution for the treatment of localized osteochondral defects in the knee.

A mouse model of renal ischemia-reperfusion injury solely induced by cold ischemia.

Transplanted kidneys usually experience several episodes of ischemia, including cold ischemia during allograft storage in preservation solution. However, previous studies focusing on cold renal ischemia were only carried out in vitro or ex vivo. In the present study, we developed and characterized an in vivo mouse model of renal ischemia-reperfusion injury (IRI) induced exclusively by cold ischemia. C57BL/6 mice underwent right kidney nephrectomy, and the left kidney was kept cool with circulating cold saline in a kidney cup, while body temperature was maintained at 37°C. We clamped the renal pedicle and flushed out the blood inside the kidney with cold saline via an opening on the renal vein. The severity of renal IRI was examined with different ischemic durations. We found that the mice with <2 h of cold ischemia exhibited no significant changes in renal function or histopathology; animals with 3 or 4 h of cold ischemia developed into mild to moderate acute kidney injury with characteristic features, including the elevation in plasma creatinine concentration and reduction in glomerular filtration rate and tubular necrosis, followed by a subsequent recovery. However, mice with 5 h of cold ischemia died in a few days with severe acute kidney injury. In summary, we generated a mouse model of renal IRI induced exclusively by cold ischemia, which mimics graft cold storage in preservation solution, and renal function can be evaluated in vivo.

The effect on early renal function of various dynamic preservation strategies in a preclinical pig ischemia-reperfusion autotransplant model.

The aims of this study were to determine the most optimal timing to start machine perfusion during kidney preservation to improve early graft function and to evaluate the impact of temperature and oxygen supply during machine perfusion in a porcine ischemia-reperfusion autotransplant model. The left kidney of an approximately 40-kg female Belgian Landrace pig was exposed to 30 minutes of warm ischemia via vascular clamping and randomized to 1 of 6 study groups: (1) 22-hour static cold storage (SCS) (n = 6), (2) 22-hour hypothermic machine perfusion (HMP) (n = 6), (3) 22-hour oxygenated HMP (n = 7), (4) 20-hour HMP plus 2-hour normothermic perfusion (NP) (n = 6), (5) 20-hour SCS plus 2-hour oxygenated HMP (n = 7), and (6) 20-hour SCS plus 2-hour NP (n = 6). Graft recovery measured by serum creatinine level was significantly faster for continuous HMP preservation strategies compared with SCS alone and for all end-ischemic strategies. The active oxygenated 22-hour HMP group demonstrated a significantly faster recovery from early graft function compared with the 22-hour nonactive oxygenated HMP group. Active oxygenation was also found to be an important modulator of a faster increase in renal flow during HMP preservation. Continuous oxygenated HMP applied from the time of kidney procurement until transplant might be the best preservation strategy to improve early graft function.

Retraction: The cryoprotectant trehalose could inhibit ERS-induced apoptosis by activating autophagy in cryoprotected rat valves.

Valvular diseases are common health problems that are strongly related to high morbidity and mortality; aortic valve allograft transplantation may be a promising way to improve survival and relieve symptoms. However, ideal tissue viability has not been observed with common valve cryopreservation methods, which could lead to apoptosis and necrosis in cryopreserved tissue. It has been observed that trehalose plays a positive role by acting to maintain cell structures and protect cells from stress responses. In this study, we studied the effects of trehalose in protecting rat valve tissue from the cooling process. We found improved higher cell function in rat valves treated with trehalose during cryopreservation than in those treated with dimethyl sulphoxide (DMSO). To further explore the mechanisms, we found that trehalose could down-regulate the expression of cleaved caspase-3, an important molecule involved in cell apoptosis. In addition, treatment with trehalose also decreased Glucose-regulated protein 78 (GRP78) and CCAAT/enhancer-binding protein homologous protein (CHOP), the key proteins in the endoplasmic reticulum stress (ERS) process. Intriguingly, we observed that trehalose promotes cryoprotected rat valve cell autophagy via an mTOR-independent but p38 MAPK-dependent signaling pathway. Additionally, miR-221 and miR-32 have been implicated in such cell activities. In summary, our study offers a new and meaningful cryopreservation approach for valve allograft storage.

Development of effective antimicrobial cocktails to prevent bacterial contamination of allograft tissues under low temperature conditions

Prevention of bacterial transmission in recipient patients via allograft decontamination with an antimicrobial cocktail consisting of cefmetazole (cefoxitin), vancomycin, lincomycin and polymyxin B is an important procedure commonly practised in tissue banks. However, some allografts are lost due to the failure of decontamination under low temperature conditions. Here, we aimed to develop new antimicrobial cocktails that exert a high bactericidal activity at 4°C. Bacterial species used in this study were selected as major causative pathogens of allograft tissue contamination. The efficacy of the combination of 2 antimicrobial agents was determined by the checkerboard titration method. The bactericidal effects of the new antimicrobial cocktails were evaluated under the same conditions as those used for the storage and preservation of allograft tissues. Among the selected antimicrobial agents, daptomycin exhibited the highest bactericidal activity against methicillin-resistant Staphylococcus aureus under low temperature conditions. The combination of daptomycin + gentamicin and daptomycin + levofloxacin showed a synergistic or additive effect against various bacterial species. The antimicrobial cocktail containing 200 μg/ml of daptomycin, gentamicin and levofloxacin could eradicate ≤104 colony-forming units/ml of methicillin-resistant S. aureus and Enterococcus faecalis, which exhibit a low susceptibility to antimicrobial agents at 4°C for 24 h. We have developed a new formula for an antimicrobial cocktail to effectively and sufficiently prevent bacterial contamination of allograft tissues under low temperature conditions in vitro.

CORM-401 Reduces Ischemia Reperfusion Injury in an Ex Vivo Renal Porcine Model of the Donation After Circulatory Death.

Carbon monoxide (CO) inhalation protects organ by reducing inflammation and cell death during transplantation processes in animal model. However, using CO in clinical transplantation is difficult due to its delivery in a controlled manner. A manganese-containing CO releasing molecules (CORM)-401 has recently been synthesized which can efficiently deliver 3 molar equivalents of CO. We report the ability of this anti-inflammatory CORM-401 to reduce ischemia reperfusion injury associated with prolonged cold storage of renal allografts obtained from donation after circulatory death in a porcine model of transplantation. To stimulate donation after circulatory death condition, kidneys from large male Landrace pig were retrieved after 1 hour warm ischemia in situ by cross-clamping the renal pedicle. Procured kidneys, after a brief flushing with histidine-tryptophan-ketoglutarate solution were subjected to pulsatile perfusion at 4°C with University of Wisconsin solution for 4 hours and both kidneys were treated with either 200 μM CORM-401 or inactive CORM-401, respectively. Kidneys were then reperfused with normothermic isogeneic porcine blood through oxygenated pulsatile perfusion for 10 hours. Urine was collected, vascular flow was assessed during reperfusion and histopathology was assessed after 10 hours of reperfusion. We have found that CORM-401 administration reduced urinary protein excretion, attenuated kidney damage markers (kidney damage marker-1 and neutrophil gelatinase-associated lipocalin), and reduced ATN and dUTP nick end labeling staining in histopathologic sections. CORM-401 also prevented intrarenal hemorrhage and vascular clotting during reperfusion. Mechanistically, CORM-401 appeared to exert anti-inflammatory actions by suppressing Toll-like receptors 2, 4, and 6. Carbon monoxide releasing molecules-401 provides renal protection after cold storage of kidneys and provides a novel clinically relevant ex vivo organ preservation strategy.

The cryoprotectant trehalose could inhibit ERS-induced apoptosis by activating autophagy in cryoprotected rat valves

Valvular diseases are common health problems that are strongly related to high morbidity and mortality; aortic valve allograft transplantation may be a promising way to improve survival and relieve symptoms. However, ideal tissue viability has not been observed with common valve cryopreservation methods, which could lead to apoptosis and necrosis in cryopreserved tissue. It has been observed that trehalose plays a positive role by acting to maintain cell structures and protect cells from stress responses. In this study, we studied the effects of trehalose in protecting rat valve tissue from the cooling process. We found improved higher cell function in rat valves treated with trehalose during cryopreservation than in those treated with dimethyl sulphoxide (DMSO). To further explore the mechanisms, we found that trehalose could down-regulate the expression of cleaved caspase-3, an important molecule involved in cell apoptosis. In addition, treatment with trehalose also decreased Glucose-regulated protein 78 (GRP78) and CCAAT/enhancer-binding protein homologous protein (CHOP), the key proteins in the endoplasmic reticulum stress (ERS) process. Intriguingly, we observed that trehalose promotes cryoprotected rat valve cell autophagy via an mTOR-independent but p38 MAPK-dependent signaling pathway. Additionally, miR-221 and miR-32 have been implicated in such cell activities. In summary, our study offers a new and meaningful cryopreservation approach for valve allograft storage.

Current insights into skin banking: storage, preservation and clinical importance of skin allografts

Current insights into skin banking: storage, preservation and clinical importance of skin allografts

Lactated Ringer-based storage solutions are equally well suited for the storage of fresh osteochondral allografts as cell culture medium-based storage solutions

BackgroundDue to the rising interest in Europe to treat large cartilage defects with osteochondrale allografts, research aims to find a suitable solution for long-term storage of osteochondral allografts. This is further encouraged by the fact that legal restrictions currently limit the use of the ingredients from animal or human sources that are being used in other regions of the world (e.g. in the USA). Therefore, the aim of this study was A) to analyze if a Lactated Ringer (LR) based solution is as efficient as a Dulbecco modified Eagle’s minimal essential medium (DMEM) in maintaining chondrocyte viability and B) at which storage temperature (4°C vs. 37°C) chondrocyte survival of the osteochondral allograft is optimally sustained. Methods300 cartilage grafts were collected from knees of ten one year‐old Black Head German Sheep. The grafts were stored in four different storage solutions (one of them DMEM-based, the other three based on Lactated Ringer Solution), at two different temperatures (4 and 37°C) for 14 and 56days. At both points in time, chondrocyte survival as well as death rate, Glycosaminoglycan (GAG) content, and Hydroxyproline (HP) concentration were measured and compared between the grafts stored in the different solutions and at the different temperatures. ResultsIndependent of the storage solutions tested, chondrocyte survival rates were higher when stored at 4°C compared to storage at 37°C both after short-term (14days) and long-term storage (56days). At no point in time did the DMEM-based solution show a superior chondrocyte survival compared to lactated Ringer based solution. GAG and HP content were comparable across all time points, temperatures and solutions. ConclusionLR based solutions that contain only substances that are approved in Germany may be just as efficient for storing grafts as the USA DMEM-based solution gold standard. Moreover, in the present experiment storage of osteochondral allografts at 4°C was superior to storage at 37°C.